Portable golf practice device

ABSTRACT

A portable golf practice device is disclosed that is easily transported by the golfer and simulates the response of natural turf when impacted by the club head during a golf swing. The device includes a base extension, which can be unfolded and slid under a platform on which the golfer stands, for maintaining stability during use. The device includes a simulated turf surface fitted in a tray. The tray rests on a base member. When a golf ball placed on the simulated turf surface is struck by a golf club, the tray and the simulated turf surface are driven forward. Means are provided to return the tray and the simulated turf surface to their original position. In its travel configuration the device folds into a compact form similar to a slim briefcase

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from provisional application Ser. No. 60/777,258 filed on Feb. 27, 2006 the content of which is incorporated herein by reference. This application is a continuation in part of application Ser. No. 11/263,210 filed on Nov. 1, 2005. This application claims the benefit of PCT application serial number PCT/US2005/047022 which is based on U.S. Ser. No. 11/070,320 and which claims a priority date of Mar. 1, 2005

FIELD OF THE INVENTION

The invention relates to golf practice devices.

BACKGROUND

To be skilled at the techniques of golf requires a golfer to practice regularly beyond the time spent on playing the game on golf courses. Many indoor/outdoor golf practice facilities have been created to accommodate golfers' need to practice, and the use of golf practice mats at these facilities is a common and long-established practice. The conventional golf practice mats are available in a variety of materials and have a surface layer simulating natural grass. These mats generally perform adequately for practicing wood shots off a tee. However, they are deficient for practicing iron shots and may actually impede the development of a correct swing.

A correct iron shot requires the golf club head to impact the golf ball on the downswing momentarily before it reaches the lowest point of the swing arc, i.e., the path of the golf club head during a swing. The descending club head will naturally remove a small patch of turf, known as a divot, below or immediately in front of the ball. Conventional golf practice mats are generally of stiff, unyielding construction and do not allow the action of taking a divot. A correct golf swing practiced on such a mat will actually produce the wrong “feel” as the club head, after hitting the ball, is impeded by and bounces off the mat. Further, to lessen the shock to the wrists and elbows and risk of injury, the golfer may alter his swing to “scoop” or sweep the ball off the mat cleanly instead of hitting “down and through” and thus develop an incorrect way of hitting iron shots. Also, when the golfer makes an incorrect swing and strikes the mat behind the ball, i.e., making a “fat” shot, the shock from hitting a hard and unyielding surface can lead to injuries to elbows and other joints. Lastly, some golf practice mats have a surface layer consisting of long fibers or inverted brushes to help reduce club head bounce and risk of injury. However, these mats may have too much “give” and more closely simulate fringe grass than fairway turf.

Many golf practice devices have been conceived over the years in an attempt to simulate the feel of hitting natural turf; some are designed to be portable so golfers can carry and use them at golf practice facilities. Examples are shown in the following U.S. patents.

U.S. Pat. No. 6,994,634 issued to the same inventors of this application discloses a device that is portable and incorporates a base extension which can be slid under a platform for maintaining stability during use. The device comprises a simulated turf surface fitted in a tray slidably positioned on a base. The tray slides forward when struck by a golf club head; means are provided to return it to its original position.

U.S. Pat. No. 6,156,396 issued to Florian discloses a device consists of a base pad formed of a resilient elastomeric material and an artificial grass carpet positioned on the base pad. When a golf ball on the carpet surface is struck, the carpet slides a limited distance and is then returned by an elastic biasing mechanism.

U.S. Pat. No. 5,888,147 issued to Luedtke discloses a device comprises an anchor piece and a divot piece connected by elastic rubber bands.

U.S. Pat. No. 5,692,967 issued to Guyer discloses a device consists of a support frame, a mat and a tray with a set of casters that roll on descending ramps attached to the frame. When a golf ball is hit from the mat, the mat and tray deflect downwardly, the mat slides partially off the tray and the tray rolls down the ramps. The mat and tray return to the original position via a tension spring means.

U.S. Pat. No. 4,955,611 issued to Moller discloses a device comprises a mat affixed on top of a bladder filled with gas or liquid and disposed within a base board. The mat and bladder slide forward and optionally downward when struck by a golf club, and are returned by spring means.

U.S. Pat. No. 4,932,663 issued to Makar discloses a device comprises an artificial turf mat suspended under tension within a rigid frame. The mat is displaced downward upon impact with a golf club. Multiple surface layers can be employed to simulate golf shots from the fairway, rough and sand trap.

U.S. Pat. No. 4,928,966 issued to Miller discloses a device comprises a frame, multiple layers disposed in spaced relation to each other on the frame, and a base attachment. The base attachment possesses guide means and rubber band means to control the sliding forward and back of the frame member.

U.S. Pat. No. 4,875,685 issued to Ballinger, et al. discloses an apparatus that includes a platform for the golfer to stand on, a main frame connected to the platform adjacent thereto, and an inner frame covered with artificial turf surface and mounted within the main frame. The inner frame pivots forward and then downward in a generally arcuate path when the surface is impacted by the golf club head. The platform can be folded to form a carrying case in which the components can be stored.

U.S. Pat. No. 4,130,283 issued to Lindquist discloses a device with artificial turf secured to a cushioned support that is movable in the direction of the ball flight and compressible when the surface is struck. The movable and compressible portion returns via a spring means.

U.S. Pat. No. 3,712,628 issued to Boss, Jr. discloses a device comprises a rigid housing containing rollers which support an endless belt with simulated grass outer surface. A platform beneath the upper portion of the belt pivots about one end and is held against the inner surface of the belt by an elastic means.

While these devices may accomplish their stated objectives to some extent, they suffer from one or more of the following limitations: (1) being too complex or too expensive to manufacture to be economically viable; (2) being too heavy or bulky to be practically transportable; (3) having a height dimension that requires the golfer to stand on an elevated platform; (4) requiring extraneous means such as spikes to anchor the device to the ground, which is impractical when the ground is hard surface such as concrete.

There exists a need for a golf practice device that is portable so the golfer can easily transport it to a golf practice facility and, when struck by a golf club head during a golf swing, yields and moves in such a manner as to simulate the response of natural turf.

SUMMARY

The present invention relates to a golf practice device that is portable, yields and moves when impacted by the head of a golf club, and more accurately simulates what the golfer experiences when hitting a golf ball off natural turf.

One aspect of the present invention provides a golf practice device that is relatively compact so it can easily be carried and transported, and does not require any means for it to be anchored or affixed to the ground or other objects. The device includes a base member and a base extension. In use, the device is placed adjacent to a practice platform, which is generally any one of the commercially available golf practice mats typically available at golf practice facilities. The base extension is unfolded and slid under the practice platform. The combined weight of the practice platform and the golfer on the base extension keeps the device stationary during use.

Another aspect of the present invention provides a golf practice device which has a surface component that yields and moves when impacted by the head of a golf club to simulate the response of natural turf. A tray rests on top of the base assembly with a simulated turf layer fitted therein. When a golf ball placed on the simulated turf layer is struck by a golf club, the force imparted to the device sends the tray together with the simulated turf layer sliding forward, thus simulating the feel of hitting natural turf. Means are provided to control the sliding forward and the retraction to their original position of the tray and the simulated turf layer.

Yet another aspect of the present invention provides a golf practice device that reduces club head bounce and lessens stress on the golfer's wrists and elbows, thus reducing negative reinforcement experienced by the golfer and increasing his confidence, which is critical to the development of a correct and reliable golf swing.

These and other aspects of the present invention will become apparent after a reading of the following description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the preferred embodiment of the portable golf practice device constructed in accordance with the present invention.

FIGS. 2 a-2 d are a series of perspective views of the portable golf practice device shown in FIG. 1 showing the base extension through the process of being folded into a transport/storage configuration.

FIG. 3 is a perspective view of the portable golf practice device shown in FIG. 1 disposed adjacent to a platform, drawn in dotted lines, for supporting a golfer.

FIG. 4 is an exploded perspective view of the portable golf practice device shown in FIG. 1 illustrating the various layers comprising the device, with the base extension omitted from the illustration.

FIG. 5 is an exploded perspective view of the base member of the portable golf practice device shown in FIG. 1 with the base extension omitted from the illustration.

FIG. 6 is an exploded perspective view of the carriage assembly of the portable golf practice device shown in FIG. 1.

FIG. 7 is a perspective view of the portable golf practice device shown in FIG. 1, with the carriage assembly and simulated turf surface in an extended position and the rail housings omitted to show the carriage retraction means.

FIG. 8 is an exploded perspective view of the channel housing embodiment of the portable golf practice device illustrating the various layers comprising the device, with the simulated turf surface omitted from the illustration.

FIG. 9 is a perspective view of the portable golf practice device shown in FIG. 8, with the carriage assembly and simulated turf surface in an extended position and the cover sections of the channel housings omitted to show the carriage retraction means.

FIG. 10 is an exploded perspective view of the parallel placement embodiment of the portable golf practice device illustrating the various layers comprising the device, with the simulated turf surface omitted from the illustration.

FIG. 11 is a perspective view of the portable golf practice device shown in FIG. 110, with the carriage assembly and simulated turf surface in an extended position and the rail housings omitted to show the carriage retraction means.

It is to be understood that like elements are identified throughout the drawings with like reference numerals.

DETAILED DESCRIPTION

The present invention relates in general to a golf practice device, and more particularly to a golf practice device that (1) is practically portable and can easily be transported by the golfer to any indoor/outdoor golf practice facility, and (2) has a surface component that yields and moves when impacted by the head of a golf club to simulate the response of natural turf and facilitate the practice and development of a correct golf swing.

The portable golf practice device according to the concepts of the present invention and how it functions can best be explained by reference to the attached drawings. As illustrated in FIG. 1, the preferred embodiment of the portable golf practice device 10 comprises a base member 20, a base extension 70, a carriage assembly 40 and a simulated turf surface 60.

As will be understood from the descriptions below, the invention comprises a base member, a carriage tray, and a carriage retraction mechanism. The carriage retraction mechanism has two portions; a guide portion and a retraction or biasing portion. The guide portion acts between the base member and the carriage tray to allow the carriage tray to guidedly move forward and rearward. The biasing portion acts between the base member and the carriage tray to control the forward movement of the carriage tray during the stroke and to retract it back to the ready to use position. Several embodiments are described. In each of the embodiments, as will be seen, the carriage retraction mechanism has both a guide portion and a retraction or biasing portion on each side which serves the several functions of holding the base member and the carriage tray together and providing the relative movement both forward for the carriage tray during the stroke and rearward during retraction.

Also, in conjunction with the base extension the device has two configurations, a travel configuration in which it is compacted to be easily transported, looking much like a thin briefcase, and an in-use configuration (see FIGS. 2 a-2 d). This is accomplished by the base extension being hingedly movable into the closed configuration and acting as the side of the portable package and then rotated outwardly to allow it to be placed beneath a platform. The bottom of the base member acts as the opposite side in the portable configuration.

Referring now to FIGS. 4, 5 and 6, the base member 20 consists of a base plate 21 that is generally rectangular in shape with its longitudinal axis generally aligned with the path of the head of a golf club during a golf swing, and a pair of parallel rail housings 22, 23 positioned along the length dimension of the base plate 21 on either side to form a frame. The rail housings 22, 23, when assembled and secured to the base plate 21, enclose cavities for receiving the carriage retraction means 43 (see FIG. 6), which are part of the carriage assembly 40 and that is detailed below with reference to FIGS. 4 and 6. The sides of the rail housings 22, 23 facing the interior of the frame have openings to allow the carriage tray 41 of the carriage assembly 40 to slide forward and retract. Mounting brackets 24 are affixed to the base plate 21 at positions determined by the length of the carriage retraction means 43, and are provided to mount and hold the carriage retraction means 43. The base plate 21 includes posts 25 with threads on the inside walls for receiving screws. After the carriage assembly 40 has been installed with the carriage retraction means 43 fitted on the mounting brackets 24, screws are used to secure and attach the rail housings 22, 23 to the base plate 21. While screws are illustrated in the drawings, it will be understood that any one of a number of securing mechanisms suitable for the material used and generally well known in the art may be employed.

Preferably, a handle 26 formed of two halves is installed on the rail housing 23 and the base plate 21, and feet 27 also formed of two halves are installed on the rail housing 22 and the base plate 21. With these preferred appendages, the device is easily portable and can be placed on any flat surface in a vertical, upright position. The base member 20 preferably includes a cushioning layer made of a resilient material that is affixed to the undersurface of the base plate 21 for support and to reduce slippage when the device is in use. The base member 20 is preferably made of a combination of metal and plastic, with the base plate 21 made of metal and the other elements made of plastic, but it can be fabricated with generally any structural material such as metal, thermoplastic or plastic, and can be either a single-piece construction or assembled from parts.

As illustrated in FIGS. 1, 2 a-2 d and 7, the base extension 70 consists of one or multiple extension plates connected to each other by hinge means and attached to the base plate 21 by attachment means 28 such as hinges or snap fasteners, allowing the base extension 70 to be folded into a transport/storage configuration. It will be noted that fastening means for securing the base extension 70 to the base member 20 while in a transport/storage configuration have been omitted and not illustrated in the drawings, as any fastening means may be employed that are commonly used and well known to one skilled in the art.

The base extension 70 is designed for the purpose of providing stability when the portable golf practice device 10 is in use. As illustrated in FIG. 3, the base extension 70 is to be unfolded and slid under a practice platform on which the golfer stands. The practice platform may be any one of the commercially available golf practice mats used at golf practice facilities, or any suitable piece of material that provides adequate cushion and has a non-skid surface that allows the golfer to maintain his footing through a golf swing. The combined weight of the practice platform and the golfer on the base extension 70 keeps the device stationary during use.

As illustrated in FIGS. 4 and 6, the carriage assembly 40 comprises a generally rectangular carriage tray 41 with sleeves 42 and dual carriage retraction means 43. Each carriage retraction means 43 further consists of a guide rail 44, one or multiple forward compression springs 45 and one or multiple rearward compression springs 46, with the compression springs 45, 46 generally having the same inner and outer diameters as the sleeves 42. The sleeves 42 are hollow tubes affixed to the sides of the carriage tray 41. To assemble, the guide rails 44 are fed through the sleeves 42 and the compression springs 45, 46 are fitted over the guide rails 44 and sandwich the sleeves 42 such that movement of the carriage tray 41 is controlled by the carriage retraction means 43. Specifically, the guide rails 44 control the direction of the movement and the compression springs 45, 46 control the velocity and distance of the movement. The assembled carriage retraction means 43 are then placed on the mounting brackets 24. The top surface of the carriage tray 41 is level and has upstanding edges on all sides. The front and the aft ends of the carriage tray 41 preferably are fitted with end caps 47 made of a resilient material such as rubber or sponge foam. The carriage tray 41 and sleeves 42 preferably are fabricated with filled and alloyed plastic composites, such as graphite-impregnated thermoplastics, which have improved abrasion resistance, lower friction, higher compressive strengths and improved creep resistance. Alternatively, an anti-friction layer or anti-friction strips made of a low-friction material may be applied to the surface of the base plate 21 or the undersurface of the carriage tray 41 to reduce friction, wear and noise.

As illustrated in FIGS. 1, 3 and 7, the simulated turf surface 60, which may be any one of the commercially available artificial turfs that are made of sturdy plastic and used for golf practice mats, generally fits the dimensions of the carriage tray 41. The simulated turf surface 60 may be adhesively bonded to the carriage tray 41 or, preferably, removably affixed to the carriage tray 41 with attaching means such as hook-and-loop fasteners.

As illustrated in FIGS. 8 and 9, an alternate embodiment of the present invention employs the same components and means with only several modifications as described below. The primary difference in this embodiment is that the guide rails 44 of the carriage retraction means 43 are replaced with a pair of parallel channel housings 29, 30 positioned along the length dimension of the base plate 21 on either side. Each of the channel housings 29, 30 is composed of a cover section and a seat section, with the seat section integral with the base plate 21. The sleeves 42 are replaced with carriage motion guides 48 which are tubes or blocks affixed to the sides of the carriage tray 41. Compression springs 45, 46 are replaced with forward and rearward compression springs 49, 50, respectively. The size, shape and dimensions of the channels formed when the cover and seat sections are closed together complement exactly the size, shape and dimensions of the carriage motion guides 48 and the compression springs 49, 50. When assembled, the carriage motion guides 48 are fitted in the channels and sandwiched between the compression springs 49, 50 such that the direction of the movement of the carriage tray 41 is guided by the channels and the velocity and distance by the compression springs 49, 50. While compression springs are illustrated in the drawings at FIGS. 8 and 9, it is to be understood that any one of a number of springs or compression-acting biasing means may be used in accordance with the present invention. Conventional securing means suitable for the specific type of spring or biasing means chosen may need to be added to the front and aft ends of the channels and the carriage motion guides 48. Also, the forward compression springs 49, could be replaced with rearward stretchable elastic members 53 and the rearward compression springs 50 could be replaced with forward stretchable elastic members 52, with suitable connection of the ends as shown in FIGS. 10 and 11 and will function as explained below but notably not requiring the guide rails shown in FIGS. 10 and 11.

A second alternate embodiment of the present invention is illustrated in FIGS. 10 and 11 and described below. The primary difference in this embodiment is that means for controlling the velocity and distance of the movement of the carriage tray 41 are positioned next to the guide rails 44, which control the direction of the movement. Compression springs 45, 46 are replaced with forward and rearward stretchable elastic members 52, 53, in the exemplary form being bungee type elastic elements with mounting attachments on the ends. Attachment brackets 51 are added to the sleeves 42 and combo mounting brackets 31, for securing both the guide rails 44 and the stretchable elastic members 52, 53, replace the mounting brackets 24. When assembled, the guide rails 44 are fed through the sleeves 42 and placed on the combo mounting brackets 31. The stretchable elastic members 52, 53 are positioned alongside the guide rails 44 and attached to the attachment brackets 51 and the combo mounting brackets 31 on the base plate 21, and are held in place under neutral biasing or slight elastic tension which places the carriage tray in a ready to use position. Thus, the direction of the movement of the carriage tray 41 is controlled by the guide rails 44 and the velocity and distance by the stretchable elastic members 52, 53. While the stretchable elastic members 52, 53 are illustrated as bungee cords and positioned alongside the guide rails 44, it will be understood that any one of a number of springs or biasing means such as rubber bands may be used and may be positioned above or below the guide rails 44 in accordance with the present invention. The attachment brackets 51 and the combo mounting brackets 31 are to be configured to match the specific type of spring or biasing means chosen.

The base extension 70 may be omitted from all of the above-described embodiments without deviating from the characteristics of the invention if (1) the base member 20 has a cushioning layer affixed to the undersurface of the base plate 21 that sufficiently reduces slippage when the device is in use, or (2) the device is deployed within a cutout in a practice platform, which supports the golfer and keeps the device stationary during use.

In use, the portable golf practice device 10 is disposed adjacent to a practice platform, which is generally any one of the commercially available golf practice mats used at golf practice facilities. The base extension 70 is unfolded and slid under the practice platform. The golfer places a golf ball on the simulated turf surface 60 and takes a swing with a golf club. Referring to FIG. 7, when the club head impacts the device, the force imparted to the carriage tray 41 compacts the forward compression springs 45 and moves the carriage tray 41, together with the simulated turf surface 60, forward as directed by the guide rails 44, thus simulating the feel to the golfer of striking a golf ball off natural turf and taking a divot. When the resistance from the forward compression springs 45 exceeds the forward force, the carriage tray 41 and the simulated turf surface 50 are then returned to their original position by the restoring force of the forward compression springs 45. Rearward compression springs 46 are employed to absorb the retraction force and reduce shock to the aft end of the device and to cooperate with the forward compression springs 45 to cause the carriage tray to return to its ready to use position. The sliding forward of the carriage tray 41 and the simulated turf surface 50 also reduces club head bounce and lessens stress on the golfer's wrists and elbows, allowing the golfer to correctly practice his golf swing and decreasing risk of injury. Referring to FIG. 11, when the club head impacts the device, the force imparted to the carriage tray 41 stretches the rearward stretchable elastic members 53 and moves the carriage tray 41, together with the simulated turf surface 60, forward as directed by the guide rails 44, thus simulating the feel to the golfer of striking a golf ball off natural turf taking a divot. When the stretching from the rearward stretchable elastic members 53 exceeds the forward force, the carriage tray 41 and the simulated turf surface 60 are then returned to their original position by the restoring force of the stretchable elastic members 53. Forward stretchable elastic members 52 are employed to absorb the retraction force and to cooperate with the rearward stretchable elastic members 53 to cause the carriage tray to return to its ready-to-use position

All of the various layers comprising the portable golf practice device 10 are fabricated to have as low a profile or height as can be practically achieved while meeting all the strength requirements. The optimal height is generally equivalent to the average height of the commercially available golf practice mats used at golf practice facilities so the golfer can practice a standard golf swing with the golf ball being generally at the same level as his feet. If the height of the device deviated materially from that of the commercially available golf practice mats, a custom, complementary practice platform would then be required, thereby resulting in a device merely movable and not realistically portable.

Regarding the length and width dimensions of the portable golf practice device 10, they are to be short enough so the device is realistically portable and long enough to form a hitting area that can easily accommodate missed hits.

To conclude, with respect to the above description, it is to be understood that the optimal dimensional specifications for the parts of the invention, including variations in number, size, shape, form, placement, material and the method of fabrication and assembly, are deemed readily apparent to persons skilled in the art upon a reading of the foregoing description, and all equivalent specifications to those illustrated in the drawings and detailed in the description are intended to be encompassed by the present invention.

Further, it will be obvious to those skilled in the art that various modifications and revisions can be made to the embodiment shown herein without departing from the spirit and essential characteristics of the invention. It is therefore intended by the appended claims to cover any and all such modifications and revisions within the scope of the present invention. 

1. A portable golf practice device for simulating the response of natural turf when impacted by the head of a golf club during a golf swing, the device comprising: a base member having spaced-apart longitudinal sides defining an operating space therebetween; a carriage tray slidably positioned on the base member for forward and rearward movement in the operating space between the longitudinal sides; a simulated turf surface on the carriage tray; and a carriage retraction mechanism comprising; a guide portion comprising a guide member on each of the spaced-apart longitudinal sides of the base member having a guide direction aligned with the forward and rearward movement of the carriage tray and a guided member on each side of the carriage tray slidingly engaged with the guide member on that side of the base member for allowing the carriage tray to guidedly slide forward and rearward; and a retraction portion comprising a biasing element on each of the spaced-apart longitudinal sides connected between the base member and the carriage tray having a substantially unbiased condition when the carriage tray is in a ready-to-use position on the base member and being biased into an energy-stored condition when the carriage tray has been moved forward; whereby upon being hit by a golf club during a swing the carriage tray will slide forward, the biasing elements will obtain energy as a restoring force and become biased, and will return the carriage tray to the ready-to-use condition and the biasing elements to a substantially unbiased condition.
 2. The portable golf practice device of claim 1 further comprising a base extension pivotably attached to the base member along one of its longitudinal sides.
 3. The portable golf practice device of claim 2 wherein the base extension has a travel position folded over or under the carriage tray and an unfolded position at about level with the base member whereby the base extension can be slid under a platform to stabilize the device when in use and can be folded over or under the base member for transport or storage.
 4. The portable golf practice device of claim 1 wherein each of the guide members comprises a guide rail supported on the base member at a forward end and at a rearward end, and the guided members comprise a sleeve extending from each side of the carriage tray and slidingly carried on the guide member on each side.
 5. The portable golf practice device of claim 4 wherein the retraction portion biasing elements comprise one or multiple forward compression springs fitted over each of the guide rails between the sleeve and the forward end of the guide rail.
 6. The portable golf practice device of claim 5 wherein the retraction portion biasing elements further comprise one or multiple rearward compression springs fitted over each of the guide rails between the sleeve and the rearward end of the guide rail, the sleeve being sandwiched between the forward and rearward compression springs such that the direction of the movement of the carriage tray is guided by the guide rails and the velocity and distance of the movement by the forward and rearward compression springs.
 7. The portable golf practice device of claim 4 wherein the retraction portion biasing elements comprise a rearward stretchable elastic member on each side of the carriage tray, each of the rearward stretchable elastic members having a forward end attached to the carriage tray on its respective side and a rearward end attached to the base member on its respective side rearwardly of the forward end so that upon forward movement of the carriage tray, the stretchable elastic members are stretched and will act to pull the carriage tray back from the forward movement such that the direction of movement of the carriage tray is controlled by the guide rails and the velocity and distance of the movement by the rearward stretchable elastic members.
 8. The portable golf practice device of claim 7 wherein the forward end of each of the rearward stretchable elastic members is attached to the sleeve on each respective side of the carriage tray.
 9. The portable golf practice device of claim 8 wherein the retraction portion further comprises a forward stretchable elastic member on each side of the carriage tray having a forward end attached to the base member on each respective side and a rearward end attached to the sleeve on each respective side whereby the interaction of the forward stretchable elastic members and the rearward stretchable elastic members will prevent excessive rearward movement of the carriage tray and will control return of the carriage tray to a ready-to-start position.
 10. The portable golf practice device of claim 1 wherein the guide portion guide members each comprises a channel housing on each side of the base member along the length dimension to form a frame, the channel housings having cavities in the form of channels and slots in the sides; and the guided members each comprises a carriage motion guide slidable inside the channels.
 11. The portable golf practice device of claim 10 wherein the retraction portion comprises one or multiple forward compression springs in each of the channel housings between a forward end of each of the carriage motion guides and a forward end of the channel housing, respectively.
 12. The portable golf practice device of claim 11 wherein the retraction portion further comprises one or more rearward compression springs in each of the channel housings between a rearward end of each of the carriage motion guides and a rearward end of the channel housing, respectively.
 13. The portable golf practice device of claim 10 wherein the retraction portion biasing elements comprise a rearward stretchable elastic member on each side of the carriage tray, each of the rearward stretchable elastic members having a forward end attached to the carriage motion guide on its respective side and a rearward end attached to the base member on its respective side rearwardly of the forward end so that upon forward movement of the carriage tray, the rearward stretchable elastic members are stretched and will act to pull the carriage tray back from the forward movement such that the direction of movement of the carriage tray is controlled by the channels and the velocity and distance of the movement by the rearward stretchable elastic members.
 14. The portable golf practice device of claim 13 wherein the retraction portion further comprises a forward stretchable elastic member on each side of the carriage tray having a forward end attached to the base member on each respective side and a rearward end attached to the carriage motion guide on each respective side whereby the interaction of the forward stretchable elastic members and the rearward stretchable elastic members will prevent excessive rearward movement of the carriage tray and will control return of the carriage tray to a ready-to-start position.
 15. The portable golf practice device of claim 2 the device having a compacted portable configuration and an in-use configuration; the base extension having an a first surface defining an outer surface and a second surface defining an inner surface and being pivotably attached along the length dimension of the device and being pivotable to an in-use open position in which the base extension may be placed under a platform and the rest of the device is in a ready-to-use position adjacent the platform and the base extension being pivotable to a compact portable configuration in which it is pivoted to a closed position adjacent the carriage tray and substantially parallel to and spaced from the base member and the second surface of the base extension faces inwardly and the outer surface faces outwardly and the carriage tray being in the space between the base extension and the base member when in the compact portable configuration; and whereby in the compact portable configuration the device has a thin compact form and in the in-use configuration the base extension can be placed under a platform. 